Fluid Mechanics (Part-4) (General Engineering) (SSC JE)

Total Questions: 41

1. An aeroplane works on- [RRB JE 28.08.2015 (Shift-III) ]

Correct Answer: (c) Bernoulli's principle
Solution:

An aeroplane works on Bernoulli's principle. According to a principle of aerodynamics called Bernoulli's law, fast moving air is at lower pressure than slow moving air, so the pressure above the wing is lower than the pressure below, and this creates the lift that power the plane upward.
Bernoulli's equation–

2. Which of the following is correct? [RRB S.S.E. 02.09.2015 (Shift-II) ]

Correct Answer: (a) Absolute pressure = gauge pressure + atmospheric pressure
Solution:


3. If the dynamic viscosity of a fluid is 0.5 poise and specific gravity is 0.5, then kinematic viscosity of that fluid in stokes is– [RRB JE 29.08.2015 (Shift-III) ]

Correct Answer: (c) 1.0
Solution:

4. The variation in the volume of a liquid with the variation of pressure is called its– [RRB JE 29.08.2015 (Shift-III) ]

Correct Answer: (b) compressibility
Solution:

Compressibility (β) - The property by virtue of which fluids undergo a change in volume under the action of external pressure is known as compressibility. It is the reciprocal of bulk modulus of elasticity (K).

5. The capillary rise at 20⁰C in clean glass tube of 1 mm diameter, containing water is: [RRB JE 29.08.2015 (Shift-I) ]

Correct Answer: (d) 30 mm
Solution:

6. Newton's law of viscosity depends upon the– [RRB JE 29.08.2015 (Shift-I) ]

Correct Answer: (c) Shear stress and rate of strain
Solution:

7. Which one of the following is defined as force per unit length– [RRB JE 29.08.2015 (Shift-I) ]

Correct Answer: (a) Surface tension
Solution:

Surface tension–It is defined as force per unit length σ = Force/Length = N/m
The tendency of fluid to maintain its surface so as the surface area will be minimum is known as surface tension.

8. The liquid used in manometer should have– [RRB JE 29.08.2015 (Shift-II) / RRB JE 26.08.2015 (Shift-II) ]

Correct Answer: (b) High density
Solution:

The liquid used in manometer should have high density so that the length of manometer can be minimize and the vapour pressure should be low for manometric fluid because high vapour pressure liquids are less sensitive to change in pressure.

9. The piezometric head in a stationary or static liquid [RRB S.S.E. 03.09.2015 (Shift-I) ]

Correct Answer: (d) Remains constant at all the points in the fluid
Solution:

10. According to principle of floatation the weight of liquid displaced as compared to the weight of the body is [RRB JE (Ranchi) 04.01.2015 ]

Correct Answer: (c) Same
Solution:

Principle of floatation–The weight of fluid (liquid) displaced is equal to the weight of the body.
• Principle of floatation is given by Archimedes.